As is well recognized in the art, ideally a wound dressing comprising an absorbent material providing a reservoir for the wound fluids diffusing from the wound should not interfere with normal wound healing. Yet, where the dressing comprises an absorbent pad of a fibrous material such as gauze which is in immediate contact with the wound, the diffusing wound fluid will extend into the interstices and around the fibers of the dressing so that the dressing is eventually adhesively and mechanically anchored into the wound surface, e.g. to graft sites, buds of new tissue forming over the wound or to the scabby protective covering for the wound.
Consequently, removal or changing of the dressing can and will cause disruption of the healing process, delaying the healing process as well as being a painful procedure for the patient.
For these reasons, wound dressings have been well known and have received wide commercial acceptance wherein the absorbent material is sandwiched between outer perforated non-adherent films preventing the dressing from sticking to the wound, being described, for example, in U.S. Pat. No. 2,923,298.
As an example of such commercial dressings, mention may be made of the TELFA.RTM. adhesive dressings and pads and the TELFA.RTM. adhesive island dressings commercially available from the Kendall Healthcare Products Company, a division of The Kendall Company, assignee of the present invention.
While they are highly efficacious in that they provide the desired protective absorbent dressing while preventing adherence to the wound, they nevertheless tend to cause skin maceration if the dressing is not changed once it becomes saturated with wound fluid. Additionally, the pooling of wound fluid on the wound surface once the dressing becomes saturated tends to diffuse laterally to undermine the adhesive outside the wound area holding the dressing to the skin.
Wound dressings are also well known in the art where a bacterial-impermeable cover sheet is provided over the absorbent fabric material to provide an aseptic environment to inhibit or preclude infection of the healing wound. Preferably the bacteria-impermeable cover is also oxygen-permeable to permit release of air within the interstices of the fabric material in order to maximize the efficiency of the absorbent fabric for receiving and retaining wound fluid before a dressing change is required. Suitable materials of this description are well known in the art and include, for example, polyurethane, a polyolefin such as polyethylene or polypropylene, "Saran" (trademark of Dow Chemical), a polyester such as polyethylene terephthalate, etc. The concept of providing a cover sheet which is oxygen-permeable, bacteria-impermeable is disclosed, for example, in U.S. Pat. Nos. 5,056,510, 5,167,613, 5,244,457 and 5,308,313 all assigned to The Kendall Company.
Stated simply, the task of the present invention is to provide a non-adherent wound dressing which obviates the above-noted problem of maceration due to pooling of wound fluid and which, additionally, can provide an environment covering the wound which can prevent ingress of bacteria.